Thread: Transmission CAN Replacement D3

Those errors also come up with low battery, charging fault and brake switch fault.

What do you mean by the transmission CAN and transmission control unit? The transmission control unit is inside the transmission, only accessible after removing the gearbox sump and control valves.

Originally Posted by loanrangie

Those errors also come up with low battery, charging fault and brake switch fault.

Th battery should not be a problem since I connect main and aux batteries together when driving around suburbs and only separate when on a trip. The alternator is less than two years old and I changed the brake light switch about 6 months ago, both jobs done as preventive maintenance. Alternator voltage is14.8v
I appreciate your input but think I have those potential problems covered.

Originally Posted by Graeme

What do you mean by the transmission CAN and transmission control unit? The transmission control unit is inside the transmission, only accessible after removing the gearbox sump and control valves.

Hi Graeme,
The transmission "CAN" referred to is located behind the main battery on the D3 so I may have misused the terminology. The part number is NNW512070 and a replacement is on order.
My question related to this item and if anyone knows whether a replacement unit would need re-calibration. If recalibation is necessary is it possible to drive the vehicle any distance or will I need to have the vehicle trucked to a service centre.
Any help with this would be welcomed

Transfer case control module (TCCM)! That is very unlikely to be the cause of your problems and if replaced then yes it has to be calibrated. If the TCCM fails then lots of canbus communications faults for modules on the high speed canbus will be reported - heaps of them, because the module is a HS canbus gateway between essential and non-essential modules on the bus.

The vehicle lowering will be because the suspension ecu will lower the car to access height for almost any brake system fault reported on the HS canbus. However as already suggested, low battery voltage could be the cause of the transmission, HDC and park brake faults if the voltage doesn't meet the minimum voltage for the gearbox and ABS modules, so you need to verify that battery voltage is OK. If OK then the external radio noise suppression capacitor mounted under the gearbox may have gone short circuit (they fail with age) causing excessive current draw from the gearbox supply - it can be removed to check if the problem is cured.

Real HDC faults would normally be caused by a faulty wheel speed sensor. However as HDC requires significant current to operate the ABS modulator and that the gearbox requires significant current to operate its solenoids and the park brake requires significant current to operate, I urge you to be very certain that battery voltage is up to scratch as a priority.

Hi Graeme. Thank you ....... and wow for all the information.
I will carefully revisit all of the items you have mentioned to see if any are the culprit(s) and report back. Fortunately I don't need to drive very far to get a result!!

Hi Graeme. I checked the battery voltage (12.2v) and the charging (14.1v) so both are OK and should not be cause of problem. I then checked the radio suppression capacitor but nothing untoward visible but I did find damage to the insulation on a wire entering another component. The small black plastic component attached to the cross member at rear of gearbox with two wires (a black one and the other white with pale blue). Insulation on the black wire is damaged. Don't know what this component does but damaged wire could potentially short out.
Having done nothing except poke at the capacitor I went for a long drive and vehicle behaved as normal. I have now taped the wires on the (??) component and will see if this fixes the problem longer term.
In view of vehicle performing normal I will change the suppression capacitor just to be safe. The capacitor is in a stupid location given all the space available on the outside of the gearbox..

Thank you for your advice. I will not proceed replacing the TCCM

Hopefully you've found the culprit although black wires are usually for earth so its worn insulation might not have been the cause. I don't know the component but will try to identify it from your description and wire colours.

The spare TCCM wont go astray as they too easily succumb to water ingress, being unsealed.